Malignant fibrous histiocytoma (MFH), subtype osteoclast-like giant cell type (A-E). Osteoclast-like giant cells (arrow head) resembling normal osteoclast are scattered throughout the lesion, especially around the calcification sites. In addition to these features, peripheral giant cells (arrow) appeared (A). Immunostaining for vimentin, desmin, α-SMA, and ED1, respectively (B-E). Tumor cells were positive for vimentin (B), and negative for α-SMA (D) and ED1 (E). Note the strong positive for desmin of smooth muscle cells of blood vessels vs. negative staining of tumor cells (C). Osteoclast-like giant cells showed positive for ED1 (E). Inflammatory cell type of MFH (F-H). This type of MHF was characterized by infiltration of various inflammatory cells (F) and ossifying matrix (G). Note the bone matrix surrounding the neoplastic fibroblasts (H). A, F and G: H&E stain, B, C, D and E: ABC method counterstained with hematoxylin, H: Azan stain. A-E: ×66, F and G: ×132, H: ×33.